NATURAL SCIENCE: 



A Monthly Review of Scientific Progress. 



No. 32. Vol. V. OCTOBER. 1894. 



NOTES AND COMMENTS. 



Protozoa from pre-Cambrian Rocks. 



ONE of the most interesting contributions to geological and bio- 

 logical science of late is Monsieur L. Cayeux's report on the 

 supposed Radiolaria and Foraminifera from the pre-Cambrian rocks 

 of Brittany. About two years ago we alluded to Dr. Charles Barrois' 

 discovery of these remarkable fossils, and announced the preparation 

 of a detailed report by M. Cayeux. The results have now appeared 

 in the Bull. Soc. Geol. France (ser. 3, vol. xxii., pp. 197-228, pi. xi.), 

 and in the Comptes Reridus (vol. cxviii., pp. 1433-1435); and there is 

 a valuable, cautiously- worded notice by Dr. George J. Hinde in the 

 last number of the Geological Magazine (Dec. 4, vol. i., pp. 417-419). 

 It appears that the supposed organisms occur in thin layers of flinty 

 rock interstratified with the pre-Cambrian schists, and they are 

 irregularly distributed, sometimes being met with singly, sometimes 

 grouped together in clusters. They are much more minute than any 

 known Radiolaria, the average size of those of the Palaeozoic rocks 

 being about seventeen times as great. The majority are simply 

 spherical in form, some are ellipsoidal, and a few are inflated or bell- 

 shaped. Some specimens exhibit radial spines, while others display 

 an inner concentric shell connected by rays with the outer test ; and 

 nearly all of the best preserved examples have a lattice-like structure. 

 M. Cayeaux recognises forty-five different forms of these fossils, and 

 assigns the majority of them to known genera, while the whole may 

 be comprised in the subordinal divisions of Radiolaria established by 

 Haeckel. 



Many of the minute bodies found with the Radiolaria, and origi- 

 nally supposed to be of the same nature, are now regarded by M. Cayeux 

 as Foraminifera ; and these also, it is interesting to note, differ from 

 later forms in being much more minute. Some of the shells are 



R 



